In a hybrid automobile in which the vehicle is driven by a combination of an engine and a motor, an idle stop, in which the engine is halted temporarily while the vehicle is stationary, is performed to reduce fuel consumption. When the vehicle is started up again after executing an idle stop, the engine is cranked by the motor and thereby restarted. However, when the engine is restarted, torque variation is generated as intake air is compressed and expanded, leading to resonance in the engine mounting system and resulting in heavy vibration.
If torque variation of an opposite phase to the torque variation is generated from the motor at this time, the torque variation can be canceled out, enabling a reduction in vibration, and hence in JP11-336581A, the torque variation in the engine is approximated by a crank angle-related third order sine wave, and torque variation of the opposite phase thereto is applied by the motor.